Unit 8 Test

Vocabulary

100

Define pentaradial symmetry, tube feet, and water vascular system. 

• Pentaradial Symmetry – radial symmetry where the organisms has body parts in multiples of five
• Tube Feet – found on the oral surface of echinoderms and help with movement, feeding and gas exchange
• Water VascularSystem – set of water-filled canals that had muscle contractions that cause vacuum suction in the tube feet (similar to the way an eyedropper works)

200

What is the tapetum lucidum? What phenomenon does it cause? 

• Tapetum Lucidum – reflective tissue behind the retina that acts like a mirror and causes rods to collect more light (this is what causes cat and dog eyes to “glow” in photographs!)

300

Define mantle, gills, shell, and tentacle.

• Mantle– outer layer of mollusks that covers body organs
• Gills– organ that uses water to exchange carbon dioxide for oxygen
• Shell– secreted by the mantle, hard outer covering of the mollusk
• Tentacle– long appendages that are attached to the head of the mollusk

400

Define radula, beak and shell. 

• Radula– a tongue-like organ with rows of teeth to scrape up food
• Beak– hard part in the mouth of squid and octopi that assists with hunting and eating prey
• Shell– secreted by the mantle, hard outer covering of the mollusk

500

What is the definition of Bivalvia, Polyplacophora, Cephalopoda, and Gastropoda? Give one example for each. 

• Gastropoda– stomach foot (their stomach is in their foot), examples are snails, sea slugs, garden slugs
• Cephalopoda – head foot (their head is in their foot), examples are squid and octopus
• Bivalvia– two shells, examples are clams, oysters, scallops and mussels
• Polyplacophora– many shells, examples are chitons

Phylum Mollusca

100

What are the four main characteristics of mollusks?

• Invertebrates with bilateral symmetry
• Have a coelom – organs are in a fluid filled cavity
• They have a soft body, which gives them the name Molluscus, meaning soft
• Most live in water but some live on land

200

How do scallops move?

• Rapidly open and close their shells to bring water in and out
• As water is forced out the scallop moves in opposite direction

300

How are pearls made?

• An irritant (grain of sand or parasite) is lodged between the shell and mantle
• Oyster secretes layers of nacre around the irritant
• Over years and years an oyster is formed

400

What did scientists learn from the study on cephalopod sensory organs (we watched a video on this!)

• Octopi are able to learn and remember information
• In the study they had two octopi in separate cages, one knew how to open a complicated box and the other did not
• The one who did not know how to open the box watched the other open the box and then used that visual information to figure out how to open the same box, without having been able to do it before

500

What are the characteristics of the circulatory system of a squid?

• 3 hearts and closed circulatory system
• Two hearts pump blood to the gills to get oxygen
• One heart pumps oxygenated blood to the body
• Blood is colored blue

Squid

100

How can we tell the ventral from the dorsal side of a squid?

• Ventral – the belly side, which we can tell because it has the siphon
• Dorsal – the back side, which we can tell because it has the fins

200

How does the structure of the ink sac lead to its function?

• Structure: Ink filled sac that is close to exit of squid
• Function: Release ink when predator is nearby to allow squid to escape, must be near the exit, so that release of ink is quick

300

How does the structure of a siphon lead to its function?

• Structure: Hollow round structure located on ventral side of squid
• Function: Moves water into and out of the squid to assist with movement

400

How do we tell if a squid is male or female?

• Male: gonad is white
• Female: gonad is yellow or clear (may be able to see eggs)

500

How does the structure of the pen lead to its function?

• Structure: Hard internal shell along the dorsal side of squid
• Function: Helps the squid keep its shape

Eyes

100

How does the eye change depending on the amount of light it is exposed to?

• Pupils become smaller when exposed to light and larger when there is little light

200

Define cornea, iris, pupil, and lens. 

• Cornea– clear bulging surface of the eye, nearly avascular, tears help keep it moist
• Iris– pigmented part of the eye that contains muscles that control the side of the pupil
• Pupil– hole through which light passes into the eye
• Lens– transparent circle that refracts (bends) light toward the retina

300

Define retina, rods and cones. 

• Retina– contains rods and cones and sends information to the optic nerve to produce images
• Rods– detect motion and basic visual information
• Cones– see color and detail

400

What is 20/20 vision? What does each number stand for? Would you rather have 20/15 or 20/40 vision? If you are wearing glasses, what should your vision ideally be?

• 20/20 vision is the average vision of all humans. The first 20 stands for the distance that the individual is from the vision chart (20 feet). The second 20 stands for what an average person would see at 20 feet.
• You would rather have 20/15 vision over 20/40 vision, because 20/15 vision means that standing at 20 feet away from the vision chart, the individual can see what the average person would see at 15 feet.
• If you are wearing glasses, your vision would ideally be 20/20.

500

Are rods or cones more important for nocturnal animals to see at night? WHY?

• Rods are more important for nocturnal animals to see at night because they detect basic motion and visual information. Nocturnal animals do not need to see color at night, so cones are less important.

Echinodermata

100

What are the general characteristics of Echinodermata?

• The endoskeleton is made of hard plates made of calcium carbonate
• Often bearing spines (For defense!)
• Adults have pentaradial symmetry
• Central disc and 5 or more radiating arms or rays
• Water-vascular system used in locomotion, attachment, and feeding

200

How do starfish digest food?

• The stomach is pushed outside the body through the mouth
• Acid in the stomach is released
• Food digested outside of stomach
• Digested food absorbed quickly afterwards

300

Why do sea stars and brittle stars have 5 rays instead of 6?

• May be advantageous because joints between the endoskeleton in the rays is never directly opposite of each other
• Having joints directly opposite of each other could make the endoskeleton weaker

400

Why do Echinodermata transition from bilateral symmetry as larvae to radial symmetry as adults?

• Unlike a bilateral symmetrical larvae, a pentaradial adult echinoderm can greet its environment from all sides and respond to it

500

What is the advantage of tube feet?

• Act like suction cups
• Grip the bottom of the ocean
• Not tossed by the waves
• Walk on ocean floor
• Feeding
• Grip prey
• Pass prey to mouth
• Gas exchange(breathing)